// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/atomicops.h"

#include <stdint.h>
#include <string.h>

#include "testing/gtest/include/gtest/gtest.h"

template <class AtomicType>
static void TestAtomicIncrement()
{
    // For now, we just test single threaded execution

    // use a guard value to make sure the NoBarrier_AtomicIncrement doesn't go
    // outside the expected address bounds.  This is in particular to
    // test that some future change to the asm code doesn't cause the
    // 32-bit NoBarrier_AtomicIncrement doesn't do the wrong thing on 64-bit
    // machines.
    struct {
        AtomicType prev_word;
        AtomicType count;
        AtomicType next_word;
    } s;

    AtomicType prev_word_value, next_word_value;
    memset(&prev_word_value, 0xFF, sizeof(AtomicType));
    memset(&next_word_value, 0xEE, sizeof(AtomicType));

    s.prev_word = prev_word_value;
    s.count = 0;
    s.next_word = next_word_value;

    EXPECT_EQ(base::subtle::NoBarrier_AtomicIncrement(&s.count, 1), 1);
    EXPECT_EQ(s.count, 1);
    EXPECT_EQ(s.prev_word, prev_word_value);
    EXPECT_EQ(s.next_word, next_word_value);

    EXPECT_EQ(base::subtle::NoBarrier_AtomicIncrement(&s.count, 2), 3);
    EXPECT_EQ(s.count, 3);
    EXPECT_EQ(s.prev_word, prev_word_value);
    EXPECT_EQ(s.next_word, next_word_value);

    EXPECT_EQ(base::subtle::NoBarrier_AtomicIncrement(&s.count, 3), 6);
    EXPECT_EQ(s.count, 6);
    EXPECT_EQ(s.prev_word, prev_word_value);
    EXPECT_EQ(s.next_word, next_word_value);

    EXPECT_EQ(base::subtle::NoBarrier_AtomicIncrement(&s.count, -3), 3);
    EXPECT_EQ(s.count, 3);
    EXPECT_EQ(s.prev_word, prev_word_value);
    EXPECT_EQ(s.next_word, next_word_value);

    EXPECT_EQ(base::subtle::NoBarrier_AtomicIncrement(&s.count, -2), 1);
    EXPECT_EQ(s.count, 1);
    EXPECT_EQ(s.prev_word, prev_word_value);
    EXPECT_EQ(s.next_word, next_word_value);

    EXPECT_EQ(base::subtle::NoBarrier_AtomicIncrement(&s.count, -1), 0);
    EXPECT_EQ(s.count, 0);
    EXPECT_EQ(s.prev_word, prev_word_value);
    EXPECT_EQ(s.next_word, next_word_value);

    EXPECT_EQ(base::subtle::NoBarrier_AtomicIncrement(&s.count, -1), -1);
    EXPECT_EQ(s.count, -1);
    EXPECT_EQ(s.prev_word, prev_word_value);
    EXPECT_EQ(s.next_word, next_word_value);

    EXPECT_EQ(base::subtle::NoBarrier_AtomicIncrement(&s.count, -4), -5);
    EXPECT_EQ(s.count, -5);
    EXPECT_EQ(s.prev_word, prev_word_value);
    EXPECT_EQ(s.next_word, next_word_value);

    EXPECT_EQ(base::subtle::NoBarrier_AtomicIncrement(&s.count, 5), 0);
    EXPECT_EQ(s.count, 0);
    EXPECT_EQ(s.prev_word, prev_word_value);
    EXPECT_EQ(s.next_word, next_word_value);
}

#define NUM_BITS(T) (sizeof(T) * 8)

template <class AtomicType>
static void TestCompareAndSwap()
{
    AtomicType value = 0;
    AtomicType prev = base::subtle::NoBarrier_CompareAndSwap(&value, 0, 1);
    EXPECT_EQ(1, value);
    EXPECT_EQ(0, prev);

    // Verify that CAS will *not* change "value" if it doesn't match the
    // expected  number. CAS will always return the actual value of the
    // variable from before any change.
    AtomicType fail = base::subtle::NoBarrier_CompareAndSwap(&value, 0, 2);
    EXPECT_EQ(1, value);
    EXPECT_EQ(1, fail);

    // Use test value that has non-zero bits in both halves, more for testing
    // 64-bit implementation on 32-bit platforms.
    const AtomicType k_test_val = (static_cast<uint64_t>(1) << (NUM_BITS(AtomicType) - 2)) + 11;
    value = k_test_val;
    prev = base::subtle::NoBarrier_CompareAndSwap(&value, 0, 5);
    EXPECT_EQ(k_test_val, value);
    EXPECT_EQ(k_test_val, prev);

    value = k_test_val;
    prev = base::subtle::NoBarrier_CompareAndSwap(&value, k_test_val, 5);
    EXPECT_EQ(5, value);
    EXPECT_EQ(k_test_val, prev);
}

template <class AtomicType>
static void TestAtomicExchange()
{
    AtomicType value = 0;
    AtomicType new_value = base::subtle::NoBarrier_AtomicExchange(&value, 1);
    EXPECT_EQ(1, value);
    EXPECT_EQ(0, new_value);

    // Use test value that has non-zero bits in both halves, more for testing
    // 64-bit implementation on 32-bit platforms.
    const AtomicType k_test_val = (static_cast<uint64_t>(1) << (NUM_BITS(AtomicType) - 2)) + 11;
    value = k_test_val;
    new_value = base::subtle::NoBarrier_AtomicExchange(&value, k_test_val);
    EXPECT_EQ(k_test_val, value);
    EXPECT_EQ(k_test_val, new_value);

    value = k_test_val;
    new_value = base::subtle::NoBarrier_AtomicExchange(&value, 5);
    EXPECT_EQ(5, value);
    EXPECT_EQ(k_test_val, new_value);
}

template <class AtomicType>
static void TestAtomicIncrementBounds()
{
    // Test at rollover boundary between int_max and int_min
    AtomicType test_val = (static_cast<uint64_t>(1) << (NUM_BITS(AtomicType) - 1));
    AtomicType value = -1 ^ test_val;
    AtomicType new_value = base::subtle::NoBarrier_AtomicIncrement(&value, 1);
    EXPECT_EQ(test_val, value);
    EXPECT_EQ(value, new_value);

    base::subtle::NoBarrier_AtomicIncrement(&value, -1);
    EXPECT_EQ(-1 ^ test_val, value);

    // Test at 32-bit boundary for 64-bit atomic type.
    test_val = static_cast<uint64_t>(1) << (NUM_BITS(AtomicType) / 2);
    value = test_val - 1;
    new_value = base::subtle::NoBarrier_AtomicIncrement(&value, 1);
    EXPECT_EQ(test_val, value);
    EXPECT_EQ(value, new_value);

    base::subtle::NoBarrier_AtomicIncrement(&value, -1);
    EXPECT_EQ(test_val - 1, value);
}

// Return an AtomicType with the value 0xa5a5a5..
template <class AtomicType>
static AtomicType TestFillValue()
{
    AtomicType val = 0;
    memset(&val, 0xa5, sizeof(AtomicType));
    return val;
}

// This is a simple sanity check that values are correct. Not testing
// atomicity
template <class AtomicType>
static void TestStore()
{
    const AtomicType kVal1 = TestFillValue<AtomicType>();
    const AtomicType kVal2 = static_cast<AtomicType>(-1);

    AtomicType value;

    base::subtle::NoBarrier_Store(&value, kVal1);
    EXPECT_EQ(kVal1, value);
    base::subtle::NoBarrier_Store(&value, kVal2);
    EXPECT_EQ(kVal2, value);

    base::subtle::Acquire_Store(&value, kVal1);
    EXPECT_EQ(kVal1, value);
    base::subtle::Acquire_Store(&value, kVal2);
    EXPECT_EQ(kVal2, value);

    base::subtle::Release_Store(&value, kVal1);
    EXPECT_EQ(kVal1, value);
    base::subtle::Release_Store(&value, kVal2);
    EXPECT_EQ(kVal2, value);
}

// This is a simple sanity check that values are correct. Not testing
// atomicity
template <class AtomicType>
static void TestLoad()
{
    const AtomicType kVal1 = TestFillValue<AtomicType>();
    const AtomicType kVal2 = static_cast<AtomicType>(-1);

    AtomicType value;

    value = kVal1;
    EXPECT_EQ(kVal1, base::subtle::NoBarrier_Load(&value));
    value = kVal2;
    EXPECT_EQ(kVal2, base::subtle::NoBarrier_Load(&value));

    value = kVal1;
    EXPECT_EQ(kVal1, base::subtle::Acquire_Load(&value));
    value = kVal2;
    EXPECT_EQ(kVal2, base::subtle::Acquire_Load(&value));

    value = kVal1;
    EXPECT_EQ(kVal1, base::subtle::Release_Load(&value));
    value = kVal2;
    EXPECT_EQ(kVal2, base::subtle::Release_Load(&value));
}

TEST(AtomicOpsTest, Inc)
{
    TestAtomicIncrement<base::subtle::Atomic32>();
    TestAtomicIncrement<base::subtle::AtomicWord>();
}

TEST(AtomicOpsTest, CompareAndSwap)
{
    TestCompareAndSwap<base::subtle::Atomic32>();
    TestCompareAndSwap<base::subtle::AtomicWord>();
}

TEST(AtomicOpsTest, Exchange)
{
    TestAtomicExchange<base::subtle::Atomic32>();
    TestAtomicExchange<base::subtle::AtomicWord>();
}

TEST(AtomicOpsTest, IncrementBounds)
{
    TestAtomicIncrementBounds<base::subtle::Atomic32>();
    TestAtomicIncrementBounds<base::subtle::AtomicWord>();
}

TEST(AtomicOpsTest, Store)
{
    TestStore<base::subtle::Atomic32>();
    TestStore<base::subtle::AtomicWord>();
}

TEST(AtomicOpsTest, Load)
{
    TestLoad<base::subtle::Atomic32>();
    TestLoad<base::subtle::AtomicWord>();
}
